Apparatus for loading boreholes



NQW FY1511 19m I. 5. H. STEWART 3,541,797

APPARATUS FOR LOADING BOREHOLES Filed Aug. 26, 1968 2 Sheets-Sheet 1SUPPLY HOPPER Mag 040.;

FIGURE 3 NW. H4, 1970 I. G. H. STEWART 3,541,797

APPARATUS FOR LOADING liofillllohms Filed Aug. 26, 1968 6 2 Sheets-Sheet2 FIGURE 6 3,541,797 APPARATUS FOR LOADING BOREHOLES Iain G. H. Stewart,Glendower, Edenvale, Transvaal,

Republic of South Africa, assignor to African Explosives and ChemicalIndustries Limited lFiletl Aug. 26, 1968, Ser. No. 755,108 Claimspriority, application Republic of South Africa, Aug. 29, 1967, 67/5,162llnt. Cl. E0211 7/24 US. Cl. 61--35 9 Claims AlBfiTlRACT OF THEDIISCLOSURE Apparatus for filling a borehole with a slurried or plasticmass. The apparatus comprises a tubular member having an open bore, atleast one flexible annular element mounted on the tubular member and aflexible hose connecting the inlet end of the tubular member to supplymeans for supplying the slurried or plastic mass.

This invention relates to loading boreholes. More particularly, itrelates to loading holes bored in civil engineering and miningoperations for the purposes of cement grouting, foundation constructionand blasting with explosives.

It is well known practice to fill or load boreholes simply by pouringthe less viscous slurries down holes, which are substantially verticalto the ground surface. Materials of a more viscous nature are placed inthe holes by being pumped through hoses inserted to varying depthswithin the holes. The principal difliculty with this loading procedureis the impossibility of seeing the rate at which the hole is beingfilled, which knowledge would enable the operator to withdraw the hoseat a similar rate. If the hose is withdrawn too slowly, it becomesembedded in the material and is likely to leave a columnar gap or cavityon being withdrawn. Conversely, if the hose is withdrawn too rapidly,the material is likely to be dropped from a height above the risingsurface of the slurry and entrap pockets of air. In most of theseoperations, discontinuity in the material filling of the hole isundesired or detrimental for the intended purpose.

The difliculty of loading materials against gravity in boreholes,slanting upwardly from the horizontal, is too well known to requireelaboration.

There is yet another problem to be solved when boreholes containsubstantial quantities of water. Slurries dropped or pumped into holesunder wet conditions may be adversely affected by too great a degree ofdilution so that, for instance, the grouting or cement mixture loses itsproperty of strength when set or the explosive mixture cannot beinitiated by a detonator or the explosion fails to propagate through themixture.

It is extremely difficult, if not impossible, to fill holes of smalldiameter with a highly viscous material and more particularly if theholes contain water.

The chief object of the present invention is to enable operators to fillboreholes more completely with loading materials than appears feasiblewith known procedures.

A further object is to load wet boreholes in such a manner that theloading materials are not deleteriously affected by the water in theholes. Other objects will become apparent from the following descriptionof the invention.

Accordingly, for filling a borehole with a slurried or plastic mass,this invention provides apparatus comprising a tubular member having anopen bore, at least one flexible annular element mounted on the tubularmember and a. flexible hose connecting the inlet end of the tubularmember to supply means for supplying the slurried or plastic mass. Theflexible annular element may be a flat 3,541,797 Patented Nov. 24,111970 ring or washer or disc of a suitable material such as natural orsynthetic rubber or a synthetic plastics material.

In order to hold the ring securely on the tubular member or nozzle ofthe apparatus, it may be seated in a groove or slot encircling thetubular member transverse to its longitudinal axis. In anothermodification of the invention, the ring may be clamped on the tubularmember by suitable means fitted to the member. Clamping and screwingdevices for securing annular fittings around the outer circumference ofpipes and tubes are well known and are, therefore, not described andillustrated in this specification. Any such mechanical means suitablefor the purpose may be employed. The major portion of the ring standsproud of the surface of the tubular member to provide a circulardisc-like structure on the body of the member.

In another embodiment of the invention, two flexible annular elementsare mounted on the tubular member. Such an arrangement assists inaligning the apparatus centrally in the hole and, thereafter, maintainsit in a position substantially co-axial with the hole during its passagethrough the hole.

In yet another embodiment of the invention, at least one of the flexibleannular elements is paired with a second, co-operating flexible annularelement of greater diameter and having performations therein to performin combination with the element as a non-return valve. The perforationsin the second flexible annular element may be orifices or slots throughits material surrounding the tubular member.

For a more complete understanding of the invention, embodiments of theapparatus and the method employed will now be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is a view in perspective of the apparatus,

FIG. 2 is a view, partly in section, of a borehole and aparatus at thecommencement of a borehole loading operation,

FIG. 3 is a view, partly in section, of a borehole and apparatus at theconclusion of a borehole loading operation,

FIG. 4 is a view in perspective of another embodiment of the invention,

FIG. 5 is a view, partly in section, of a borehole and the apparatusillustrated in FIG. 4 at the commencement of a borehole loadingoperation, and

FIG. 6 is a view, partly in section, of a borehole and the apparatusillustrated in FIG. 4 at the commencement borehole loading operation.

Referring to the drawings in which similar parts are indicated by likenumerals, FIG. 1 shows the complete assembly of tubular member 4,flexible annular elements 5 and 6 and flexible hose 7. The tubularmember 4 is illustrated as a nozzle with an open bore, the inlet end ofwhich communicates with the bore of the hose 7 and the outlet ordischarge end of which is shown at 8. The hose 7 covering the inlet endof the nozzle 4 may be fastened thereto by a circular clip but, usually,the grip of the hose over the end of the nozzle is sufficiently tight toprevent disengagement during a loading operation. The end of the hose 7remote from the nozzle 4 is connected to supply means, such as a pump, apressurized slurry container or a mixer-placer unit provided with a pump(not shown), for supplying the slurry or plastic mass under pressure tothe nozzle 4. In these drawings, the flexible annular elements 5 and 6are flat neoprene rings or discs secured in shallow, circular grooves asat 9 and 10 on the nozzle 4.

In practice, the apparatus is pushed down a borehole 11 by means of hose7 until it is felt to have touched the bottom of the hole as illustratedin FIG. 2. If there is water in the hole, it is displaced past therearwardly flexed neoprene rings. The neoprene rings and 6 are thenflexed into the opposite direction by slightly retracting hose 7. Atthis stage, the neoprene rings 5 and 6 act as flexible seals between thenozzle 4 and the wall 12 of the borehole 11. Pumping of the slurry orplastic mass is then started.

As soon as the spaceas defined by the wall 12 and the face of theborehole, the neoprene ring 5 and the surface of the nozzle 4 projectingfrom itis filled with the mass 13, the pressure exerted by the dischargefrom outlet 8 of the continuing flow of mass 13 forces the apparatus torise in the borehole 11. If there is water as indicated by referencenumeral 14, lying in the borehole, it may have been urged to flow pastthe ring 5 by the mass 13 and will then be raised by the piston actionof the nozzle as the nozzle is displaced from the bottom of the hole.The neoprene rings act as barriers to separate the mass 13 from thewater 14 as well as to ensure that the space forwardly of ring 5 in theborehole 11 is completely filled with the mass 13.

As the apparatus begins to rise in the borehole, the neoprene rings 5and 6 are flexed in the direction as shown in FIG. 3. In this trailingposition, the efficiency of the seal improves with the increase ofpressure differential across the neoprene ring 5. A portion of the mass13 may escape into the space between the two rings 5 and 6 due tosurface irregularities in the borehole. However, this action will onlyfurther serve to ensure that the borehole 11 is completely filled withmass 13 to the exclusion of water 14 and unwanted air gaps.

It will be understood that the assembly of nozzle 4 and neoprene rings 5and 6 acts as a sealing piston in the borehole 11, while accommodatingvariations in the diameter of the borehole, which may be likened to acylinder. Moreover, the operator does not have to exercise any controlover the rate of speed of withdrawal of the apparatus from the borehole.Having inserted the apparatus in the borehole and reversed the flexureof the flexible rings, he may then let it be ejected at a controlledrate, which is governed entirely by the rate at which the borehole 11 isbeing properly filled by mass 13.

The conclusion of the borehole loading operation is illustrated in FIG.3, at which stage the pumping of the mass 13 through hose 7 is stopped.There may be a marker on the hose 7 adjacent the inlet end of the nozzle4 as a visual warning to the operator to stop pumping or, if desired,pumping may be stopped as soon as the inlet end of the nozzle appears atthe mouth of the borehole 11. The apparatus is then removed from theborehole 11 and inserted into another borehole, when the loadingprocedure described above is repeated.

It will be seen from the illustration in FIG. 3 that the water 14 hasbeen almost completely expelled from borehole 11 and has overflowed fromits mouth. The very minor volume of water shown may be removed entirely,if so desired, by continuing the pumping operation until the mass 13rises to the mouth of borehole 11. In any event, much of this waterwould be removed by the rings 7 6 and 5 in withdrawing the apparatusfrom the borehole.

If mass 13 is an explosive composition, any water left in the boreholeafter withdrawal of the apparatus may be removed and/ or absorbed by thestemming material, such as rock cuttings or rubble, which may be pouredinto the hole to cover the explosive composition according to normalblasting practice.

Referring now to FIG. 4, in which is depicted a modification of theassembly shown in FIG. 1, reference nu meral 15 indicates a tubularmember with an open bore, such as a nozzle. Its inlet end communicateswith the bore of flexible hose 16 and that end of the nozzle 15 may besecured within the hose 16 by means of a fastener or circular clip 17,if considered necessary. The outlet or discharge end of the nozzle 15 isshown at 18. The free end of the hose 16 is connected to supply means,such as a pump or pressurized supply hopper (not shown), for supplyingthe slurry or plastic mass under pressure to the nozzle 15. In thisassembly, there is illustrated one pair of flexible annular elementsintended to act in combination as one unit 19. There may be more thanone such unit 19 mounted on nozzle 15 or there may be both the type 5and 6 and the type 19 of flexible annular elements mounted on the samenozzle.

Element 20 is similar to elements 5 and 6 of FIG. 1 but element 21 is ofgreater diameter than element 20 and has perforations through itsmaterial such as, for instance, slots 22. Preferably, element 20 may beas shown and is of a size which gives little, if any, contact with thewall of the borehole for which it has been selected as having suitabledimensions.

The method for filling a borehole 11, when using the assembly of FIG. 4,follows the same steps as are described above with reference to FIGS. 2and 3. This description will be amplified with reference to FIGS. 5 and6 to explain more exactly the action of the paired elements 20 and 21,co-operating to perform as a unit 19 or flexible annular element 19.

In charging a borehole 11 with a plastic or slurried mass 13 though atubular member 15 fitted with one or more paired flexible annularelements 20 and 21, the perforated element 21 is flexed rearwardly asshown in FIG. 5 by frictional contact with the wall 12 of the borehole11 as the member 15 is pushed down the hole 11. This action separatesthe two elements 20 and 21 of the pair 19 and allows water 14, which maybe contained in the hole 11, to pass the periphery of the leading, orfirst, non-perforated element 20 of smaller diameter and then escapethrough the perforations 22 of the second, or trailing, element 21. Inthe passage of the apparatus down the hole 11, the water 14 is thusdisplaced beyond the apparatus without the latter becoming anobstruction in the way of the water. On reaching the bottom of the hole,element 21 is flexed in the opposite direction as previously described.When the mass 13 is pumped through the apparatus and fills the spacebetween the face of the borehole and the leading element 20 to cause theapparatus to rise in the borehole 11, the second or perforated element21 is flexed in the opposite direction to press against thenon-perforated element 20, as shown in FIG. 6. This action closes theperforations 22 and the build up of pressure, created by the mass 13being pumped into the borehole 11, forces the element 20 against theelement 21 and ensures a firm and positive closure of the perforations22. The pair 19 of elements 20 and 21 then act as a single unit in thesame manner as element 5 or element 6 in the alternative embodiment ofthe invention shown in FIG. I and described above.

For larger holes filled with water, it may require considerable force topush the nozzle, on which is mounted flexible annular elements of thetype illustrated in FIG. 1, down to the bottom of the hole. Where suchconditions are encountered, it may be advantageous to use the type ofelement shown in FIG. 4.

Where the rock face is fissured, it is known to use liners of plasticsmaterial to ensure the retention of the explosive medium in theborehole. This procedure presents no difficulties in the use of theapparatus and method of the invention since the plastics liner isreadily threaded over the nozzle and hose prior to its insertion in thehole. In fact, the placing of the liner is facilitated by this procedurein comparison with the conventional practice of weighting the bottom ofthe liner with a weight such as a boulder. Filling of the borehole withthe explosive slurry than proceeds as described above.

Several trials of the method and apparatus of the invention wereconducted at different locations to test the efliciency of operation.All these trials were successful and are described in the followingexamples.

EXAMPLE I Tests were carried out at the semi-technical plant ofapplicant. A vertical pipe, having a bore of four inches and a length oftwenty feet, was filled with water. Using a positive displacement pump,having a two inch outlet, and seventy feet of plastic tubing of two inchbore connected to the apparatus assembly as exemplified by FIG. 1, thepipe was completely loaded with a dummy explosive slurry. It wasobserved that the water flowed evenly from the pipe as the apparatusfilled it with the slurry and that the apparatus rose steadily in thepipe during the loading operation. The temperature of the water flowingfrom the pipe did not fall, indicating that there had not been anymixing with the particulate urea in the dummy slurry, which would havelowered the temperature of the resulting solution formed and dischargedfrom the pipe. The quantity of slurry estimated to fill the pipecorresponded very nearly with the volume of the pipe.

This test was repeated twice with equally good results.

EXAMPLE II The test conducted in Example I was repeated three times,using two of the units 19--as illustrated in FIG. 4 as the flexibleannular elements mounted on the nozzle in place of the two ringspreviously used.

The three tests produced excellent results.

EXAMPLE III The test conducted in Example II was repeated but in theabsence of water. The dry pipe was loaded successfully to its fullcapacity with the dummy explosive slurry, indicating that no air gapswere interrupting the continuity of the slurry column.

EXAMPLE IV The test conducted in Example II was repeated but in theabsence of water. The dry pipe was loaded successfully to its fullcapacity with the dummy explosive slurry, indicating that no air gapswere interrupting the continuity of the slurry column.

EXAMPLE V A test was conducted in the quarry of the Mooiplaas DolomiteQuarry at Cordelfos in the Transvaal. Six holes were drilled in looseboulders on the quarry floor measuring one and a half inches in diameterby five feet in depth. Two of these holes were horizontal while fourholes sloped upwardly from the horizontal level at various anglesbetween fifteen to twenty degrees. Only one ring, of the typeexemplified by FIG. 1, was mounted on the nozzle. Each hole was loadedby the apparatus with six pounds of an explosive slurry composition.

On detonation, the blast was successful.

EXAMPLE VI A test was conducted in a stope on the property of theVlakfontein Gold Mining Company near Springs, Transvaal, on thefollowing boreholes, which had been drilled a long time previously andwere extremely irregular because of rock movement.

6 crater holes measuring 1 /2 inches diameter by 36 inches deep.Horizontal.

3 crater holes measuring 1 /2 inches diameter by 72 inches deep.Horizontal.

stope holes measuring 1 /2 inches diameter by 42 inches deep. Angleddownwardly and full of water.

The poor condition of the holes made this test an unfair one andconsiderable difficulty was experienced in inserting and ejecting thenozzles. Nevertheless, the crater holes and eight of the stope holeswere charged with a pumpable, explosive slurry composition through anozzle on which was mounted one ring of the type exemplified by FIG. 1and the ensuing blasts were successful.

EXAMPLE VII A test was conducted in a stope on the property of theVlakfontein Gold Mining Company on the following boreholes, which hadbeen drilled just prior to the time of the test.

7 stope holes measuring 1 /2 inches diameter by 42 inches deep and atangles slightly above and below horizontal.

2 stope holes measuring 1 /2 inches diameter by 42 inches deep andhorizontal.

8 holes in the drive at various angles below the horizontal level andall full of water.

The apparatus worked smoothly with one ring, of the type exemplified byFIG. 1, mounted on the nozzle and all holes were loaded with a pumpable,explosive slurry composition.

The blasts were successful.

EXAMPLE VIII A test, included in simulated shaft sinking experiments onthe property of the Vlakfontein Gold Mining Company, was conducted oneight boreholes measuring one and a half inches by five feet deep. Fourof these holes were vertical cut holes and four holes, which surroundedthe cut holes, were easers. The cut holes are blasted first and thesubsequent blasting of the easers widens the hole created by the firstblasting operation.

The working place was flooded to a depth of about six inches under waterafter completion of the borehole drilling. All eight holes were thenloaded with a pumpable, explosive slurry composition through anapparatus assembly as exemplified by FIG. 1.

The loading operation and subsequent blasting of the holes werecompletely successful.

EXAMPLE IX A test was conducted on the floor of the quarry of theMooiplaas Dolomite Quarry during a pop shooting or secondary blastingoperation. This is an operation, which takes place after the mainblasting operation, to break up oversize material too heavy for removalor treatment.

Forty holes, measuring one and a quarter inches in diameter by lengthsvarying from one to two feet in depth, were drilled into large boulders.The holes were then charged with a pumpable, explosive slurrycomposition through a nozzle on which was mounted one ring of the typeexemplified by FIG. 1.

The loading operation and subsequent shattering of the boulders byblasting the charges in the holes were completely successful.

An advantage of the present invention is that it provides a means forloading boreholes at any inclination to the horizontal.

A further advantage is that the apparatus enables the proper filling ofholes of small diameter with viscous masses. The size of the hole willdetermine the choice of size of nozzle and rings. Furthermore, fairlylarge variations in borehole diameters may be accommodated by a givenset of flexible rings.

I claim:

ll. For filling a borehole with a slurried or plastic mass, apparatuscomprising a tubular member having an open bore with an inlet for supplyof said mass and an outlet therefor at the opposite end thereof, atleast one flat flexible annular element mounted on the tubular member ofa dimension larger than the borehole and adapted for continuouscircumferential contact with said borehole, said element being flexedrearwardly by contact with the borehole as said member is moved into andout of said hole, said element functioning to serve as a barrier to massdischarged into said borehole from said outlet so that said tubularmember is moved out of said borehole by the action of said dischargedmass against said element as the borehole is filled, and a flexible hoseconnecting the inlet end of the tubular member to supply means forsupplying the slurried or plastic mass.

2. Apparatus as claimed in claim 1 in which the element is a fiat ring,washer or centrally holed disc.

3. Apparatus as claimed in claim 1 in which the element is of a naturalor synthetic rubber or a synthetic plastics material.

4. Apparatus as claimed in claim 1 in which the element is mounted onthe tubular member by being seated in a groove or slot encircling themember transverse to its axis.

5. Apparatus as claimed in claim 1 in which two elements are mounted onthe tubular member.

6. Apparatus for filling a borehole with a slurried or plastic mass,said apparatus comprising a tubular member having an open bore, at leastone flexible annular element mounted on the tubular member and aflexible hose connecting the inlet end of the tubular member to supplymeans for supplying the slurried or plastic mass, at least one of theflexible annular elements being paired with a second, co-operatingflexible annular element of greater diameter and having perforationstherein to perform, in combination with the element as a non-returnvalve.

7. Apparatus as claimed in claim 6 in which the perforations in thesecond flexible annular element are orifices or slots through itsmaterial surrounding the tubular member.

8. Apparatus as claimed in claim 1 in which the supply means is a slurrypump or pressurized supply hopper.

9. For filling a borehole with a slurried or plastic mass, apparatuscomprising a tubular member having an open bore, at least one flexibleannular element mounted on the tubular member and a flexible hoseconnected to the inlet end of the tubular member, the free end of theflexible hose being adapted for connection to means for supplying theslurried or plastic mass, at least one of the flexible annular elementsbeing paired with a second, cooperating flexible annular element ofgreater diameter and having perforations therein to perform incombination with the element as a non-return valve.

References Cited UNITED STATES PATENTS 2,719,768 10/1955 Webber.2,729,067 1/1956 Patterson e 6153.58 3,255,592 6/1966 Moor 6153.64

REINALDO P. MACHADO, Primary Examiner P. C. KANNAN, Assistant ExaminerUS. Cl. X.R. 61-45, 53.64

